jz4725

I thought the point of the jz4725 was to be a jz4740-SX (16-bit
instead of 32-bit databus) to eliminate one RAM chip and to use LQFP
instead of BGA, both measures meant to lower cost and to compete with
comparable Rockchip 2706 designs.
It seems strange to add it back, but of course there's now the new
jz4725b that allows booting from SD, so you can sacrifice the flash
chip to avoid requiring more space.